TMZ first reported that Slice, whose given name was Kevin Ferguson, was rushed to a Florida hospital on Monday night and American Top Team, the gym where he trained, sent out a tweet wishing their condolences.

“The ATT Family and South Florida community lost a legend today. RIP Kimbo,” the team wrote.

Sources confirmed to MMAFighting.com's Ariel Helwani that Slice had died. The cause of death was unclear.

One of the most popular and polarizing figures in MMA history, Slice came to prominence in the early 2000s through a series of backyard brawl videos that were massive hits online.

Eventually, he made the transition to organized MMA and brought in massive ratings whenever he fought. He would eventually make it to the UFC, earning a unanimous decision victory over Houston Alexander in 2009 and then suffering a TKO loss to Matt Mitrione in 2010.

Slice returned to the ring in 2015 with Bellator, where he beat Ken Shamrock last June and then fought Dada 5000 earlier this year, but that fight was ruled a no-contest after Slice tested positive for a banned substance.

“We battled inside the cage, warrior vs. warrior. Outside the cage, we have loved ones. REST IN PEACE KIMBO SLICE. May God Watch Over You,” Shamrock wrote on Twitter.